In recent years, in a semiconductor device for controlling power in a hybrid vehicle, or an electric vehicle, or in a CPU for a high speed computer, or the like, achievement of high thermal conduction in a package material has been desired to avoid an excessive increase in a temperature of a semiconductor thereinside. More specifically, capability of effectively dissipating heat generated from a semiconductor chip to an outside has become important.
Specific examples of a method for solving such an issue of heat dissipation include a method for dissipating heat by bringing a high thermal conductive material (heat-dissipation member) into contact with a heat generation site to lead heat to an outside. Specific examples of the high thermal conductive material include an inorganic material such as metal and metal oxide. However, such an inorganic material has a problem in processability, insulation or the like, and is significantly difficult in single use as a packing material of a semiconductor package. Therefore, development has been made on the heat-dissipation member in which a composite of the inorganic materials and a resin is formed to achieve high thermal conduction.
The high thermal conduction of a resin composite material has been generally achieved by adding a large amount of a metallic filler or an inorganic filler to a general-purpose resin such as a polyethylene resin, a polyamide resin, a polystyrene resin, an acrylic resin and an epoxy resin. However, thermal conductivity of the inorganic filler is a value inherent to a substance, and has an upper limit. Therefore, an attempt has been widely made on a method for improving thermal conductivity of a resin to achieve bottom-up of the thermal conductivity of the composite material.
Patent literature No. 1 discloses a heat-dissipation member obtained by polymerizing a liquid crystal composition by performing alignment control by an alignment control additive or by a rubbing treatment method or the like as a method for improving the thermal conductivity of the resin.